Pure Substances and Mixtures

A classmate wrote: "My conclusion is correct because it matches my prediction." What should you tell them?

• Correct, because predictions must always match conclusions.

• Incorrect, because conclusions should be based on data, not just predictions.

• Correct, because hypotheses are always right.

• Incorrect, because predictions are never written in science reports.

You want to test the effect of sunlight on plant growth. Which is the BEST plan?

• Grow two plants, one in sunlight and one in darkness, measure height daily for two weeks.

• Grow one plant anywhere and measure it after two weeks.

• Put many plants outside and water them randomly.

• Leave a plant indoors without observation.

Why is it important to use standard units when taking measurements?

• To make measurements faster

• To ensure consistency and accuracy in data

• To avoid using conversion tables

• To make numbers smaller

A student measures the length of a book as 25 cm. What is this measurement in meters?

• 0.025 m

• 0.25 m

• 2.5 m

• 25 m

Which data table title BEST organizes the measurement of boiling water at different altitudes?

• "Temperature Data"

• "Boiling Point of Water at Different Altitudes (°C)"

• "Altitude vs Water"

• "Table of Liquids"

You want to organize the mass of different fruits measured in grams. Which is the BEST way?

• Write them in a paragraph

• Make a data table with two columns: Fruit and Mass (g)

• Draw random pictures of fruits

• Record in any order without units

Which statement correctly describes the roles of solute and solvent?

• Solvent is the substance that dissolves; solute is the one being dissolved.

• Solute is always water, solvent is always solid.

• Solute and solvent cannot be in the same state.

• Solvent disappears completely after mixing.

If sugar is dissolved in hot tea, which component is the solvent?

• Sugar

• Tea (liquid part)

• Both sugar and tea

• Neither

Which of the following best describes percent by mass?

• The amount of space occupied by matter.

• The amount of matter in an object

• It is the volume of solute in a given volume of solution expressed in milliliters solute per 100 milliliters of solution

• It is the amount of solute in each mass of solution expressed in grams solute per 100 grams solution

What will happen to the concentration if the solute amount stays the same but more solvent is added?

• The concentration increases.

• The concentration decreases.

• The concentration remains the same.

• The solution becomes saturated.